The present invention relates to a magnetic disk drive and, more particularly, to the structure of a magnetic head for use in a magnetic disk drive.
Magnetic disk drives for writing and reading data out of hard disks, stationary disks or similar magnetic disks are extensively used today. This kind of disk drive is usually loaded with a plurality of disks and a plurality of heads each being associated with respective one of the disks. Each of the heads has a slider including an electromagnetic transducer for writing and reading data, a gimbal spring retaining the slider, a pressing spring connected at one end thereof to the gimbal spring to press the slider against one side of the disk, and a generally right-angled triangular rigid arm to which the other end of the pressing spring is affixed. On the other hand, the disk drive has a positioning device for supporting the arms of the magnetic head arranged one above another, a plurality of disks mounted on a spindle, and a base plate supporting the positioning device and spindle. Generally, this type of disk drive brings the heads to a particular track position by closed loop control. Specifically, one of the heads is implemented as an exclusive servo head adapted for tracking control while one side of a particular disk associated with the servo head is provided with a servo surface. The servo head is movable together with the other heads, or data heads, and accesses the servo surface of the particular disk, thereby reading a positioning signal or servo signal thereoutof. The servo signal is used to position the heads at a desired track position. Hence, the servo head and the servo surface are prevented from being dislocated from each other, and so are done the data heads and the associated sides of the other disks.
However, the problem with the above-described disk drive is that the disk drive itself heats up as it is operated over a long period of time or due to changes in ambient conditions such as temperature elevation. Temperature elevation is also brought about by windage loss ascribable to the rotation of the disks. Such a temperature elevation causes various structural members of the disk drive, e.g., the heads, disks, positioning device, and base plate to thermally expand and thereby change the dimensions thereof. Although the changes in dimensions of this nature do not effect the relative position of the servo head and servo surface, they dislocate the data heads and the associated surfaces of disks to cause a so-called thermal off-track to occur. This prevents a high track density, mass magnetic disk drive from being implemented.